The skin of an aircraft typically provides aerodynamic surfaces on aircraft components such as the fuselage. The skin panels that form the skin may be subjected to structural and aerodynamic loads. Aerodynamic pressure loading, which is the primary loading on the skin, arises from a pressure differential between the inside and outside of the aircraft. The pressure loading is approximately orthogonal to the skin surface in an out-of-plane direction. Stringers and frames are typically added to stabilize the skin from buckling due to structure loads. The skin itself typically is thickened, or stiffened, to avoid buckling under some load conditions. A common limitation to the weight of a fuselage skin panel is the inability to separate the structural loads from the aerodynamic loads. In the case of an unpressurized fuselage, the skin is sized by the loads that are associated with aerodynamic loads only. In order to transfer the fuselage bending loads to a separate structural element, the skin must be able to move independently of the structural element, while still maintaining an aerodynamic outer surface.
One solution is to incorporate fuselage bending loads in the skin. While this approach makes sense for a pressurized fuselage, it results in a large weight increase due to the increase in skin thickness to account for the additional loads.